The present invention relates generally to the field of tube extracting devices, and more particularly to an improved tube extracting device for facilitating the removal of tubes from different types of structures, such as boilers, condensers, evaporators, and the like.
A typical condenser comprises a pair of parallel tube sheets, a plurality of baffle plates, and a plurality of heat exchanger tubes. The tube sheets are located at the ends of the condenser. The baffle plates are positioned between the tube sheets and generally parallel thereto. The heat exchanger tubes extend between the tube sheets and through the baffle plates and are supported by the tube sheets. The tube sheets and baffle plates have a series of aligned holes formed therein, and the heat exchanger tubes are inserted through these holes and then expanded in the areas of the tube sheets into fluid-tight pressure contact therewith.
Because of malfunctions or normal preventive maintenance, it may be necessary to remove one or all of the tubes from the structure. This is generally accomplished by first relieving the pressure forces between the tubes and the tube sheets and then longitudinally pulling the tubes through the baffle plates and the tube sheets. Various types of devices are used to initially relieve or break the secured connection between the tubes and tube sheets, and then another apparatus is used to withdraw the tubes from the structure.
In the refurbishing of a water-tube boiler and the replacing of the tubes thereof, the tubes are conventionally removed by the use of an air hammer or the like, chipping away at the tube connection to the drum, to physically force the tube from the associated opening in the boiler drum. These methods have often resulted in damage to the drum and the opening through which the tube stub section projected.
Another method often used for removing tubing from structures is by use of a cutting torch. This is particularly common in the case of large boilers using heavy walled tubing on the order of three inches in diameter. Errors in use of the cutting torch can, of course, damage the tube sheet requiring expensive refinishing and repair work.
Prior art believed to be relevant to the present invention includes U.S. Pat. No. 4,233,730 issued to Godbe, U.S. Pat. No. 4,231,246 to issued Gorenc et al., and U.S. Pat. No. 4,180,903 issued to Hannigan, Jr., as well as, U.S. Pat. No. 2,507,201 issued to Evans, U.S. Pat. No. 2,744,429 issued to Seely and U.S. Pat. No. 3,245,247 issued to Valente.
The Godbe patent discloses a crimping tool having a hydraulic-driven ram which drives a wedge into the outside wall of the tube to crimp the tube. The crimping operation breaks the bond between the tube and tube sheet and allows the tube to be pushed from the hole.
A crimping tool for crimping a boiler tube to facilitate its removal is disclosed in the Gorenc patent.
The Hannigan, Jr. teaches a hydraulic-driven apparatus having a plurality of arms with gripping fingers for engaging and crimping the tube.
The Evans patent discloses a one-piece cutter or plow-type tool for slitting the tubes from the outside of the tube sheet to break the bond between the tube and the tube sheet.
The Seely patent teaches a particular type of tube crimper used in reducing the cross-section of a capillary tube to provide a precise flow resistance.
The Valente patent teaches a complicated device for pointing the end of tubing so that the tubing may be inserted into a drawing die.
There is a need for a simpler device for facilitating the removal of tubing, especially heavy-walled tubing from drums and/or tube sheets without damaging the drum and/or tube sheet bonding surfaces.